At the present time, a number of various processes are available for separating and recovering deuterium and tritium, wherein deuterium (D) and tritium (T) refer to elemental hydrogen isotopes having either one or two additional neutrons respectively in a hydrogen nucleus.
A temperature exchange process is one of such processes that utilize isotope exchange reactions between the hydrogen compounds. The reactions utilize such an isotope effect that, for example, when water and hydrogen sulfide gas, each at the same deuterium concentration, are mixed together the deuterium concentration in water will become higher than that of the hydrogen sulfide gas in the equilibrium state.
Also known in the prior art is the use of a dual temperature isotope exchange system that separates and enriches hydrogen isotopes with higher efficiency. This process is basically a combination of two temperature exchange reactors, one at a low temperature and the other at a high temperature. The exchange reactions to be utilized in the dual temperature process include exchange reactions between water and hydrogen sulfide gas. The exchange reaction between water and hydrogen sulfide gas has an advantage that it avoids the necessity of the use of a catalyst in the reaction, but has a disadvantage in that the separation coefficient dependent upon chemical equilibrium is small.
The use of the catalyst substantially promotes an exchange reaction rate between water and hydrogen sulfide gas. For this reason, the development of a hydrophobic, highly efficient isotope exchange reaction catalyst has progressed greatly.